James McKeown started in goal, with Mills, Shaun Pearson and Danny Collins forming the defence.

The midfield was completely changed, with Maxwell lining up behind Davies, Osborne, Sam Jones and Danny Andrew, as Asante and Vernon formed a new-look strike partnership.

Disley, Vose, Bolarinwa, Comley and Dyson were all named as substitutes, along with Adi Yussuf and Andrew Boyce.

Portsmouth were looking to continue a run of good form which had seen them rise to occupy the third automatic promotion place, with Paul Cook’s men coming into the game after a 4-0 win at Colchester at the weekend.

The first chance of the game was created by the hosts on two minutes and saw Baker create some space before firing a shot over the bar.

The Mariners responded with a cross from Andrew which fell for Asante, although his attempt deflected off a defender and went out for a corner. The ball from it was cleared but Town kept possession and a shot by Mills from 20 yards hit the post.

Naismith called McKeown into action for the first time on seven minutes but his near-post effort was comfortably stopped by the keeper.

Town had started well though, and Asante drew a save from home keeper David Forde three minutes later, forcing him to push a curling shot out for a corner.

But when the opening goal came on 12 minutes, it was the hosts who took the lead. A shot from BENNETT took a heavy deflection off Collins, which caused the ball to loop over McKeown and into the net.

Portsmouth immediately went in search of another goal and a shot from Naismith again took a big deflection, although this time, the only damage was a corner.

At the other end, Jones looked to create an opening for Asante but the offside flag went up against the striker.

Another opportunity for the home side came on 25 minutes when a header from Naismith went just wide of the target, before he also missed with a shot from distance soon afterwards.

Vernon was the next to shoot off-target for Town after a cross from Davies came out to him, before a ball into the box from Naismith was cleared by the Mariners defence as Portsmouth attacked again.

Asante was penalised for a foul which could have been given the other way on 34 minutes and after Portsmouth took the free kick short and built play up down the right, they eventually doubled their advantage when a shot by ROSE deflected off Davies and went past McKeown.

A cross from Naismith was pushed clear by McKeown before an attacker could get on the end of it for what would have been a tap-in on 42 minutes, with the home side on top as half-time loomed.

An injury to goalscorer Bennett forced him off two minutes before the break, with Gary Roberts coming on in his place.

Three added minutes were signalled to be played at the end of the half and in the first of them, the hosts made it 3-0 when BAKER cut in from the right and played a one-two with Gareth Evans before beating McKeown at his near post.

No further chances came before the half-time whistle, with Portsmouth firmly in control of the contest after the Mariners had made a promising start.

No changes were made before the restart and the second half got off to the worst possible start for Town as they conceded again within 30 seconds. Portsmouth created an opening for a shot by Baker and after it was not held by McKeown, NAISMITH reacted first to make it 4-0.

The hosts still went in search of more goals and Baker was the next to try a shot after a cross fell for him. This time though, the ball cleared the crossbar.

A home penalty claim was turned down by referee Robert Jones after a challenge by Osborne, before the Mariners won a corner at the other end but Vernon could not trouble keeper Forde from Davies’ delivery as his header went wide.

Town boss Bignot made a double substitution on 56 minutes, sending Disley on for Jones and Comley on in place of Osborne.

Another Grimsby corner came on the hour but it caused no problems for the Portsmouth defence as Andrew’s delivery was caught by Forde.

A spell of Town possession provided some brief encouragement for the 527 travelling supporters before the offside flag went up as Andrew played the ball into the home penalty area.

Asante won a corner on 67 minutes, which came to nothing, before Jamal Lowe came on in place of Naismith for the hosts.

Baker forced McKeown to push his shot out for a corner at the other end three minutes later.

Lowe crossed for Michael Doyle to head just wide soon afterwards, before a shot went wide after Maxwell had lost possession on 79 minutes.

Yussuf replaced Asante in the Town front-line for the last 10 minutes, before a shot from Lowe on the edge of the box was blocked.

The home side’s third and final substitution saw Conor Chaplin come on for Eoin Doyle with four minutes remaining.

Two added minutes were signalled to be played at the end of the game and Portsmouth closed the remainder of the time out to record back-to-back 4-0 wins.

Town will look for an improvement when they host Crawley Town at Blundell Park on Saturday.